<template>
  <a-table
    :rowKey="rowKey"
    :columns="columns"
    :dataSource="dataSource"
    :expandedRowKeys="expandedRowKeys"
    v-bind="tableAttrs"
    v-on="$listeners"
    @expand="handleExpand"
    @expandedRowsChange="expandedRowKeys = $event"
  >
    <template v-for="slotItem of slots" :slot="slotItem" slot-scope="text, record, index">
      <slot :name="slotItem" v-bind="{ text, record, index }"></slot>
    </template>
  </a-table>
</template>

<script>
import { getAction } from '@/api/manage'

export default {
  name: 'JTreeTable',
  props: {
    rowKey: {
      type: String,
      default: 'id'
    },
    // 根据什么查询，如果传递 id 就根据 id 查询
    queryKey: {
      type: String,
      default: 'parentId'
    },
    queryParams: {
      type: Object,
      default: () => ({})
    },
    // 查询顶级时的值，如果顶级为0，则传0
    topValue: {
      type: String,
      default: null
    },
    columns: {
      type: Array,
      required: true
    },
    url: {
      type: String,
      required: true
    },
    childrenUrl: {
      type: String,
      default: null
    },
    tableProps: {
      type: Object,
      default: () => ({})
    },
    /** 是否在创建组件的时候就查询数据 */
    immediateRequest: {
      type: Boolean,
      default: true
    },
    condition: {
      type: String,
      default: '',
      required: false
    }
  },
  data() {
    return {
      dataSource: [],
      expandedRowKeys: []
    }
  },
  computed: {
    getChildrenUrl() {
      if (this.childrenUrl) {
        return this.childrenUrl
      } else {
        return this.url
      }
    },
    slots() {
      let slots = []
      for (let column of this.columns) {
        if (column.scopedSlots && column.scopedSlots.customRender) {
          slots.push(column.scopedSlots.customRender)
        }
      }
      return slots
    },
    tableAttrs() {
      return Object.assign(this.$attrs, this.tableProps)
    }
  },
  watch: {
    queryParams: {
      deep: true,
      handler() {
        this.loadData()
      }
    }
  },
  created() {
    if (this.immediateRequest) this.loadData()
  },
  methods: {
    /** 加载数据*/
    loadData(id = this.topValue, first = true, url = this.url) {
      this.$emit('requestBefore', { first })

      if (first) {
        this.expandedRowKeys = []
      }

      let params = Object.assign({}, this.queryParams || {})
      params[this.queryKey] = id
      if (this.condition && this.condition.length > 0) {
        params['condition'] = this.condition
      }

      return getAction(url, params)
        .then(res => {
          let list = []
          if (res.result instanceof Array) {
            list = res.result
          } else if (res.result.records instanceof Array) {
            list = res.result.records
          } else {
            throw '返回数据类型不识别'
          }
          let dataSource = list.map(item => {
            // 判断是否标记了带有子级
            if (item.hasChildren === true) {
              // 查找第一个带有dataIndex的值的列
              let firstColumn
              for (let column of this.columns) {
                firstColumn = column.dataIndex
                if (firstColumn) break
              }
              // 定义默认展开时显示的loading子级，实际子级数据只在展开时加载
              let loadChild = { id: `${item.id}_loadChild`, [firstColumn]: 'loading...', isLoading: true }
              item.children = [loadChild]
            }
            return item
          })
          if (first) {
            this.dataSource = dataSource
          }
          this.$emit('requestSuccess', { first, dataSource, res })
          return Promise.resolve(dataSource)
        })
        .finally(() => this.$emit('requestFinally', { first }))
    },

    /** 点击展开图标时触发 */
    handleExpand(expanded, record) {
      // 判断是否是展开状态
      if (expanded) {
        // 判断子级的首个项的标记是否是“正在加载中”，如果是就加载数据
        if (record.children[0].isLoading === true) {
          this.loadData(record.id, false, this.getChildrenUrl).then(dataSource => {
            // 处理好的数据可直接赋值给children
            if (dataSource.length === 0) {
              record.children = null
            } else {
              record.children = dataSource
            }
          })
        }
      }
    }
  }
}
</script>

<style scoped></style>
